smog

noun

ˈsmäg 

ˈsmȯg

: a fog made heavier and darker by smoke and chemical fumes

also : a photochemical haze caused by the action of solar ultraviolet radiation on atmosphere polluted with hydrocarbons and oxides of nitrogen especially from automobile exhaust

smogless

ˈsmä-gləs 

ˈsmȯ-

adjective

Synonyms of smog

• haze
• fog
• cloud
• mist

Examples of smog in a Sentence

the city's smog was once so bad that darkness often prevailed, even at noon

Recent Examples on the Web

Cars, trucks and other forms of transportation emit 60% of the smog in California and 40% of the state’s greenhouse gas emissions. — Paul Rogers, Mercury News, 7 Aug. 2026

Ahead of Thursday’s meeting, the AQMD also added conditions to mandate that Lineage continue tracking ammonia, smog-forming emissions and toxic air contaminants. — Tony Briscoe, Los Angeles Times, 6 Aug. 2026

Opponents point to research showing emissions from higher blends could worsen summer smog while encouraging the conversion of grasslands for corn farming. — Makenzie Huber, States Newsroom, 6 Aug. 2026

Rain can increase visibility when there’s smog, but its effect on air pollution is less certain, the weather service said. — Finnegan Belleau, Chicago Tribune, 19 July 2026

Word History

Etymology

smoke + fog

First Known Use

1880, in the meaning defined above

Phrases Containing smog

• anti-smog

Rhymes for smog

• blog
• bog
• clog
• cog
• dog
• flog
• fog
• frog
• grog
• hog
• jog
• log

Kids Definition

smog

noun

ˈsmäg 

also ˈsmȯg

: a thick haze caused by the action of sunlight on air polluted especially by smoke and automobile exhaust fumes

Etymology

from smoke and fog

Medical Definition

smog

noun

ˈsmäg also ˈsmȯg

: a fog made heavier and darker by smoke and chemical fumes

also : a photochemical haze caused by the action of solar ultraviolet radiation on atmosphere polluted with hydrocarbons and oxides of nitrogen especially from automobile exhaust